The present invention relates to a moving-map display with the recording of the map on a photographic film.
Moving-map displays of the aforementioned type are used for displaying a moving geographical or topographical map on board a vehicle and are more particularly used for aerial navigation. In connection with the latter the image of the map displayed on a cathode-ray indicator represents the overflown area and to the same map are generally added symbols and markings relative to navigational parameters and to the position of the aircraft. The displayed image must move in the same way as the ground beneath the aircraft and its positioning must therefore be automatically controlled in x, y and .theta., corresponding respectively to the longitude, latitude and heading data of the aircraft, said data being supplied by the navigational system equipping the aircraft. The moving-map display incorporates a computer which processes, on the basis of the aforementioned data, image position servo-control signals in x, y and .theta..
French Pat. No. 2,357,022, corresponding to U.S. Pat. No. 4 138 726 describes a moving-map display incorporating the map recorded on a photographic film carried by spools, a video image reader on the basis of a line-by-line scan, means for the automatic control of the image as a function of the latitude, longitude and heading and switching circuits for the video image reading signals. The video image reader incorporates either a light source and a television camera, or a flying-spot tube and a photodetector (photomultiplier or the like), optical elements for image transfer and focusing and a camera or flying-spot tube scanning signal generator. In the case of a colour film it is necessary to add a trichromatic optical filter and three photodetectors or shooting cameras in place of one element.
The on-board computer processes as a function of the heading .theta. the scanning voltage corrections for rotating the image by a corresponding quantity, as a function of the latitude y a film position servo-control by rotating the spools, and as a function of the longitude x a mirror position servo-control ensuring, by optical deflection of the light radiation emitted by the source or flying-spot, the corresponding displacement of the scanned image. The switching signals incorporate a TV monitor preceded by circuits for video mixing with the symbol signals or for carrying out a desired processing or for local video channel switching operations.